A 4-year-old boy is brought to the emergency department by his parents following a seizure. The patient has had an upper respiratory illness for the last 2 days but has no previous history of seizures. Today, he suddenly became unresponsive and his arms and legs started shaking for approximately 40 seconds. The patient was alert when the paramedics arrived at his house. In the emergency department, temperature is 40 C (104 F) and pulse is 110/min. The patient appears tired but is alert and cooperative. Physical examination shows clear nasal discharge and mild pharyngeal erythema but no nuchal rigidity or other neurologic deficits. Which of the following is the most likely underlying cause of this patient's seizure?

Question

A 4-year-old boy is brought to the emergency department by his parents following a seizure.  The patient has had an upper respiratory illness for the last 2 days but has no previous history of seizures.  Today, he suddenly became unresponsive and his arms and legs started shaking for approximately 40 seconds.  The patient was alert when the paramedics arrived at his house.  In the emergency department, temperature is 40 C (104 F) and pulse is 110/min.  The patient appears tired but is alert and cooperative.  Physical examination shows clear nasal discharge and mild pharyngeal erythema but no nuchal rigidity or other neurologic deficits.  Which of the following is the most likely underlying cause of this patient's seizure?

Quizplus · Accepted Answer

11ec160b_3b05_7f81_9249_b7791e2c7df5_MD0001_00 This patient's presentation is consistent with febrile seizure, a generally benign neurologic condition characterized by seizure and elevated temperature (≥38 C [100.4 F]) without signs of CNS infection (eg, nuchal rigidity) or metabolic abnormality. Children age 6 months to 5 years are almost exclusively affected because seizure threshold is lower during early years of brain development. In addition, young children are particularly susceptible to febrile viral illnesses (eg, roseola, influenza) associated with high fever (≥39.5 C [103 F]), a key risk factor for development of seizures due to hyperthermia-induced neuronal dysfunction. A simple febrile seizure is characterized by a generalized seizure (eg, unresponsiveness, tonic-clonic movements) that is short (<15 min) and does not recur within 24 hours. Benzodiazepines can be used to abort seizures lasting ≥5 mins; however, most self-resolve prior to presentation. Treatment primarily involves antipyretics (eg, nonsteroidal anti-inflammatory drugs), which decrease fever by inhibiting prostaglandin E₂ synthesis and counteracting the effects of circulating cytokines, resulting in reduction of the thermoregulatory set point in the hypothalamus. (Choice B) Microbial invasion of the meningeal layers occurs with meningitis, a serious infection that may progress to encephalitis and trigger generalized seizures. However, meningitis causes other findings not seen in this patient, such as nausea/vomiting, photophobia, nuchal rigidity, and prolonged confusion (ie, persisting after post-ictal period). (Choice C) Neuronal injury from cross-reacting antiviral antibodies describes acute cerebellar ataxia, which often occurs in children following a viral illness but presents with gait instability, impaired coordination, and tremor. (Choice D) Severe neuronal loss and gliosis in the hippocampus (ie, hippocampal sclerosis) causes mesial temporal lobe epilepsy. Although this condition is associated with a history of childhood febrile seizures, it usually presents in young adults as focal-onset seizures (rather than generalized-onset seizures) characterized by unilateral motor symptoms, a rising epigastric sensation, and auditory/olfactory auras. (Choice E) Absence seizures are initiated by synchronized slow-wave discharge of thalamocortical tracts. Although these seizures are more common in children with a history of febrile seizures, they are characterized by staring spells of <20 seconds, not unresponsiveness for 40 seconds with shaking movements. Educational objective: Febrile seizure is usually a benign neurologic disorder that occurs most commonly in children age 6 months to 5 years who have high fever due to a viral illness. The pathophysiology involves hyperthermia-induced neuronal dysfunction triggering a short (<5 min) generalized seizure; treatment is generally supportive with antipyretics for fever reduction. __________ References: Febrile seizures. (http://www.ncbi.nlm.nih.gov/pubmed/26286537)

A 4-Year-Old Boy Is Brought to the Emergency Department by His